fix(wpadmin): Fix URL sanitization for handling Unicode

[veryard]

Replaced sanitize_text_field() with esc_url_raw() for sanitizing URLs passed via $_REQUEST['url']. This change fixes an issue where the URL example.com/หน้าภาษาไทย would incorrectly return example.com// due to improper sanitization when clicking on the Customize button through the admin bar.

This ensures that URLs containing non-Latin characters are correctly preserved and prevents unexpected behavior in the customizer.

Happy to hear feedback on this approach or if there's a better way to handle this scenario! Let me know if this change introduces any concerns.

Trac ticket: https://core.trac.wordpress.org/ticket/61317

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Props veryard, dilip2615.

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[github-actions]

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[dilipom13]

Yes, it's working properly.

[swissspidy]

Do we also need to use esc_url_raw here, since it's also a URL?